[alsa-devel] "ALSA: HD-Audio: SKL+: abort probe if DSP is present and Skylake driver selected" breaks sound, suspend on Apollo Lake

[Pierre-Louis Bossart]

On 12/25/18 7:10 AM, Hans de Goede wrote:
> Hi Pierre-Louis,
>
> Since I recently have been doing a bunch of i915 work I'm currently
> running drm-tip. This brought in this commit from next:
>
> https://cgit.freedesktop.org/drm-tip/commit/?id=c337104b1a16becc486fdc95d544c835b17021db 
>
>
> This causes the hda driver to not bind to the audio on my Apollo Lake
> based laptop, and the asoc driver errors out with:
>
> [   19.176417] skl_hda_dsp_generic skl_hda_dsp_generic: Unsupported 
> HDAudio/iDisp configuration found
> [   19.176428] skl_hda_dsp_generic: probe of skl_hda_dsp_generic 
> failed with error -22
>
> After which I get no sound and worse, the machine hangs on suspend.
> It seems to never reach its fully suspended state (the power-led
> never starts to fade on/off as it normally does when suspended).
>
> I've been looking through the Kconfig option and it seems that
> currently selecting SND_SOC_INTEL_APL makes little sense since there
> are 0 machine drivers for this setup ?
>
> I guess I can fix this by unselecting SND_SOC_INTEL_SKYLAKE and
> then during the manual platform selection not selecting
> SND_SOC_INTEL_APL, but IMHO we need to put something in place
> where the hda driver actually checks if there is a machine driver
> and if there isn't one then we should keep using the hda driver
> on the machine in question.

Interesting, thanks for the bug report.

There are three problems here:

0. How did this work before? if you didn't have a blacklist, you had two 
drivers registering for the same PCI ID, so were relying on an implicit 
behavior.

1. why does the HDaudio support in the SKL driver fail?  I am not sure 
what's going on here. If your device has the DSP enabled, then the 
HDaudio SKL part should just work. It works on my APL NUC.  Would you 
mind sharing the .config and full dmesg log with -DDEBUG enabled for 
sound/soc/codecs and sound/soc/intel? The "unsupported configuration 
found" typically means the i915 driver isn't working or creating the 
iDISP codec since we assume HDMI is always present.

2. how do we 'backtrack' in case the SKL driver fails? That one I don't 
have a good solution for. You should be well past the firmware 
initialization steps and at this point it's too late to return -ENODEV 
to let the legacy audio take over.


>
> Regards,
>
> Hans
>
>
> p.s.
>
> Merry Christmas!
>
>
>